Holly good morning and thank you for writing.
With the screen two things get old: the emulsion and the fabric.
The emulsion gets old after about two thousand passes.
The fabric gets old after about twenty thousand passes.
When the emulsion gets old, you can remove it with a specific product called "stripper", wash very well, let it dry, and then recoat it with a new layer of emulsion.
When the fabric gets old, you must remove it, then stretch the frame with a new fabric.
When the frame gets old I suggest you throw it away.

This is Franco Ratto,